029
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View 029 as PDF for free.
More details
- Words: 596
- Pages: 4
0-7803-7185-2/02/$10.00 ©2002 IEEE
113
0-7803-7185-2/02/$10.00 ©2002 IEEE
114
Pump chamber Inlet
Flow channel
ruler
Drain port
pressure sensor
Outlet 20 mm
Reservoir
Supply port
35 mm
(a) Flow Rate Measurement
(a) micro pump chip
(b) Pressure Measurement
Figure 7. Schematic of experimental setups.
Outlet 3 mm
(c) inlet Pump chamber 0.5 mm Inlet
(b) pump chamber
(d)outlet
Figure 6. Photograph of the completed micro pump and SEM images of the pump chamber, the inlet and the outlet channel. chamber, two diffusers and flow channels was formed by Deep Reactive Ion Etching (DRIE) process, as shown in Fig. 5 (4)-(6). The remaining thickness of the silicon for the pump chamber was available as a diaphragm. After removing the silicon dioxide layers, a indium tin oxide (ITO) layer was formed on the opposite surface of the silicon substrate. A pyrex glass plate with supply and drain ports was stacked on the silicon by anodic bonding. A 70 µm thick PZT plate was mounted on the diaphragm with glue, as shown in Fig. 5 (7)-(8). Figure 6 shows a photograph of the completed micro pump with size of 20 mm x 35 m m x 0.7 mm and SEM images of the pump chamber with size of 0.5 mm x 3 mm and the inlet/outlet channels. EXPERIMENTS The displacement of the diaphragm, flow rate and pressure were evaluated for the characteristics of the completed micro pump. The micro pump was set in a polycarbonate flame with electrical probes and fluid connectors for measurement of flow rate and pressure. As a fluid connector, silicone tubes of 2 mm inner diameter were used. Figure 7 (a) and (b) show the experimental setups of flow
0-7803-7185-2/02/$10.00 ©2002 IEEE
rate and pressure of the micro pump, respectively. The driving waveforms were supplied to the electrical probes on PZT plate by a function generator in combination with an amplifier. The displacement of the PZT plate surface was directly measured by a Laser Doppler Vibrometer (LDV) to estimate the displacement of the diaphragm on the pump chamber. The flow rate was measured from the averaged speed of liquid level under almost the same static pressure at the inlet and the outlet. The generated pressure at the outlet (forward direction) was measured by setting a pressure sensor at the end of the tube connected to the drain port. The pressure was measured at zero flow rate with keeping the inlet open and the outlet closed. The pump was turned on after the pressure reaching the equilibrium state. The generated pressure at inlet (backward direction) was measured in the same way as forward direction by setting the pressure sensor on the supply port side. RESULTS AND DISCUSSIONS Figure 8 shows the displacement of the diaphragm at different voltage of 1 kHz sine wave. The theoretical values analyzed by FEM were compared with the experimental results. The experimental values were about 70 % less than the theoretical ones. This discrepancy was thought to be caused by inadequate poling of PZT, location error of PZT, thickness error of diaphragm and effect of glue layer. Figure 9 and Figure 10 show the flow rate and the generated pressure of the micro pump as a function of driving voltage (height of waveform) at 11 kHz of repeating frequency, respectively. The theoretical values were shown in the same graph. Bi-directional pumping was successfully confirmed. The pumping direction was switched over by changing the shape of waveform and the flow rate was adjusted with good controllability in a range from 15 nl/s to 220 nl/s by changing the
115
0-7803-7185-2/02/$10.00 ©2002 IEEE
116
113
0-7803-7185-2/02/$10.00 ©2002 IEEE
114
Pump chamber Inlet
Flow channel
ruler
Drain port
pressure sensor
Outlet 20 mm
Reservoir
Supply port
35 mm
(a) Flow Rate Measurement
(a) micro pump chip
(b) Pressure Measurement
Figure 7. Schematic of experimental setups.
Outlet 3 mm
(c) inlet Pump chamber 0.5 mm Inlet
(b) pump chamber
(d)outlet
Figure 6. Photograph of the completed micro pump and SEM images of the pump chamber, the inlet and the outlet channel. chamber, two diffusers and flow channels was formed by Deep Reactive Ion Etching (DRIE) process, as shown in Fig. 5 (4)-(6). The remaining thickness of the silicon for the pump chamber was available as a diaphragm. After removing the silicon dioxide layers, a indium tin oxide (ITO) layer was formed on the opposite surface of the silicon substrate. A pyrex glass plate with supply and drain ports was stacked on the silicon by anodic bonding. A 70 µm thick PZT plate was mounted on the diaphragm with glue, as shown in Fig. 5 (7)-(8). Figure 6 shows a photograph of the completed micro pump with size of 20 mm x 35 m m x 0.7 mm and SEM images of the pump chamber with size of 0.5 mm x 3 mm and the inlet/outlet channels. EXPERIMENTS The displacement of the diaphragm, flow rate and pressure were evaluated for the characteristics of the completed micro pump. The micro pump was set in a polycarbonate flame with electrical probes and fluid connectors for measurement of flow rate and pressure. As a fluid connector, silicone tubes of 2 mm inner diameter were used. Figure 7 (a) and (b) show the experimental setups of flow
0-7803-7185-2/02/$10.00 ©2002 IEEE
rate and pressure of the micro pump, respectively. The driving waveforms were supplied to the electrical probes on PZT plate by a function generator in combination with an amplifier. The displacement of the PZT plate surface was directly measured by a Laser Doppler Vibrometer (LDV) to estimate the displacement of the diaphragm on the pump chamber. The flow rate was measured from the averaged speed of liquid level under almost the same static pressure at the inlet and the outlet. The generated pressure at the outlet (forward direction) was measured by setting a pressure sensor at the end of the tube connected to the drain port. The pressure was measured at zero flow rate with keeping the inlet open and the outlet closed. The pump was turned on after the pressure reaching the equilibrium state. The generated pressure at inlet (backward direction) was measured in the same way as forward direction by setting the pressure sensor on the supply port side. RESULTS AND DISCUSSIONS Figure 8 shows the displacement of the diaphragm at different voltage of 1 kHz sine wave. The theoretical values analyzed by FEM were compared with the experimental results. The experimental values were about 70 % less than the theoretical ones. This discrepancy was thought to be caused by inadequate poling of PZT, location error of PZT, thickness error of diaphragm and effect of glue layer. Figure 9 and Figure 10 show the flow rate and the generated pressure of the micro pump as a function of driving voltage (height of waveform) at 11 kHz of repeating frequency, respectively. The theoretical values were shown in the same graph. Bi-directional pumping was successfully confirmed. The pumping direction was switched over by changing the shape of waveform and the flow rate was adjusted with good controllability in a range from 15 nl/s to 220 nl/s by changing the
115
0-7803-7185-2/02/$10.00 ©2002 IEEE
116
